Excavation induced response of pile foundations

In urban areas excavations for construction of basements, tunnels and other underground facilities inevitably influence the existing pile foundations. Due to the release of stresses during excavations, confining pressures around existing piles decrease significantly inducing additional deflections and bending moments. It is important to quantify these effects at the design stage, in order to protect the existing structures during nearby deep excavations. In this paper, the impact of excavation induced ground movements on adjacent pile groups is investigated. Numerical simulations based on the finite element method are performed on free-head and capped-head piles in different pile configurations. The problem was modelled considering the three-dimensional geometry, which facilitates to simulate the arching and shielding effect of piles within a group. The response of both interior and peripheral piles is investigated. Results show that the presence of front piles reduces the detrimental effects on the rear piles within the group. In addition the provision of a pile cap significantly reduces the deflection of pile group due to load transfer to the rear piles, which are located away from the wall supporting the excavation. Outcomes of this research will contribute towards the design and construction of resilient pile foundations.